1. Field of the Invention
The present invention relates to a polymer, an ink and an organic film.
2. Description of the Related Art
Polyphenylene is a substance which has heat-resistance and exhibits electroconductivity when an oxidizing agent (electron acceptor) and a reducing agent (electron donor) are added (see Synthetic Metals, Vol. 1., p. 307 (1987); “Electroconductive polymer”, KYORITSU SHUPPAN CO., LTD., p. 4; and “Polymer Battery”, KYORITSU SHUPPAN CO., LTD., p. 15). In addition, many findings regarding the polyphenylene have been reported. For example, it is reported that the polyphenylene exhibits electroluminescence; the polyphenylene exhibits electrochromism and, therefore, is electrochemically active; and the polyphenylene can be carbonized (e.g., baked) to thereby obtain carbon material (see J. Phys. Chem. Vol. 100, p. 12631 (1996); Advanced Materials, Vol. 4, p. 36; and J. Mater. Res. Vol. 13, p. 2023).
Unfortunately, unmodified polyphenylene is, however, insoluble in a solvent and cannot be thermally melted. Accordingly, the unmodified polyphenylene is difficult to be molded and is incapable of being thinned. For that reason, various attempts have been made to solubilize the polyphenylene. For example, it is reported that a soluble polyphenylene can be obtained by polymerizing phenylenes having different binding sites such as polyphenylene and paraphenylene (see Japanese Patent (JP-B) No. 3733527, and Chem. Lett., 721 (2000)). However, the above method cannot confer satisfactory solubility on the resultant polyphenylene. Additionally, the resultant polyphenylene has a low degree of polymerization and unsatisfactory film-forming property. On the other hand, an attempt has been made to obtain a soluble and meltable polyphenylene by polymerizing monomers in which, for example, a long-chain alkyl or alkoxy group is introduced. For a polyphenylene-based polymer in which aromatic rings are added to a backbone thereof, a similar method has been also used for obtaining solubility and meltability. There has been disclosed that a polyphenylene-based polymer which is soluble in an organic solvent and is moldable can be obtained by polymerizing 1,4-dialkylbenzene compounds (see JP-B No. 3103138).
Thus, although various methods have been disclosed, most of them include introducing a dissolvable group such as an alkyl group and an alkoxy group into a side-chain (see JP-B No. 3078011). They are not suitable for obtaining heat stability, electron transport property and luminescence property, which are physical properties due to inherent properties of the polyphenylene such as stiffness and π electron-rich property. There has been no disclosure that clearly describes a method for conferring solubility on the polyphenylene while keeping a stiff structure thereof. Generally, the dissolvable group (bulk group) tends to inhibit electroconductivity. Therefore, solubility and electroconductivity are difficult to be achieved together.
A stiff polyphenylene polymer which has been made to be soluble by introducing a suitable dissolvable group, and thus can be thinned is expected to be utilized as a member for organic electronics, in particular, a semiconductor member, a conductor member, an electroluminescence member, an electrochromism member or an engineering plastic member.